Automatic excess heat protector, especially for electric machines and apparatus



Se t; 20 1927. 1,642,953

P w. HlcKr-:L ET AL AUTOMATIC EXCESS HEAT PROTECTOR, ESPECIALLY FOR ELECTRIC 'MACHINES AND APP ARATus Filed Dec. 4. 1924 Patented Sept. 20, 1927.

i UNITED STATES PATENT oFEicE.A

WILHELM HICKEL, OF ZURICH, AND OTTO PLETSCHER, JR., OF ALBISRIEDEN, NEAR ZURICH, SWITZERLAND.

AUTOMATIC EXCESS HEAT PROTECTOR, ESPECIALLY FOR ELECTRIC MACHINES AND` APPARATUS.

Application led December 4, 1924, Serial No. 753,820, and in Germany December 31, 1923.

This invention relates to an automatic eX- cess heat protector for the protection of machines and apparatus against. overheating. The protector comprises a case within which there is arranged a cartridge Jfor cut-outs formed by a guide with aV slide movable therein in longitudinal direction, a spring pressing on the slide, a fuse arranged in a chamber and preventing the slide from moving longitudinally, the slide being arranged on a plunger, one end of the plunger being connected with said spring and the other end with the fuse. It the latter blows, a warning or safety signal is released. In a suitable construction ot my improved protector an electric switch is actuated by the longitudinal movement ot the plunger carrying the slide, which slide may be constructed to close or to open a circuit. This switch may be arranged on the inside or on the outside of the case enclosing the guide and the slide. Suitably the slide may be formed as a current bridge arranged at a right angle withvthe dii rection of the guide, so that the contact making parts are arranged outside of the range otboth guides. It by the movement of the slide aI circuit is to be closed by this move'- ment the contact .making parts get inA contact with two current-carrying poles, if however by the movement ot the slide a closed circuitl is to be opened, bythis movement the contact making parts are removed from the current-carrying poles. the poles being arranged on the inner wall ot the case and connect-ed with two terminals on the outside of the case. Suitably the chamber enclosing the fuse may be formed separate of the roo-m within the case, 'for instance by a capped nut screwed on the lower end of the case, so that the fuse when blowing cannot be injurious to the guide and the slide.

Some constructions according to my invention are illustrated in the accompanying drawings by way of example.

Figs. 1 and 2 each are a vertical section il` lustrating one form of device constructed in accordance with the present invention.

Fig. 3 is a cross-section on line A-A ot Fig. 1.

Fig. 4 is a view from below of Fig. 1.

Referring to the drawing a shell 1 of insulating material such as fibre is provided with two lateral projections 2. A connecting terminal 3 is secured within each projection 2 and covered by an insulating protectlng cover 4 threaded on the terminal 3. The terminals 3 are provided with contact surfaces 5 situated within the shell 1 and making contact with two bolts 6. The bolts 6 are movably` mounted within a tube 7 `and pressed by a small helical spring toward the contact surfaces 5 in order to insure good Contact with them. Each of the bolts 6 is guided in a longitudinal slot 10 of the tube 7 by means of a small pin 9. A plunger 12 of insulating material is arranged within a socket 13 mounted in the shell 1, the tube 7 being secured within a transverse bore ot' a guide portion or slide 11 formed on the plunger 12. The guide portion 11 projects through a wide transverse slot 14 of the socket 13 into a guide slot 15 formed in the inner wall of the shell 1. The socket 13 is provided with a flange 16 adapted to be seated. on the end of the shell 1. At the upper end of the plunger 12 there is secured a head 17 by mea-ns of a screw. A helical spring 18 is supported by a disc 19 mounted on the flange 16 and presses against the head 17, the disc forming'a guide for the upper part of the plunger 12. The disc- 19 and the socket 13 are pressed on the shell 1 by means of a capped nut 20. A pin 21 havmg a head 22 is secured to the lower end of the plunger 12. 23 designates a disc-shaped fuse, the melting-point ot which is predetermined aecording to thel permissible heating temperature of the apparatus or -machine equipped with the automatic excess heat protector. In order to be mounted on the pin 21 the fuse is provided with a recess 24. The lower end 25 or" the socket 13 is threaded, a cap 26 made of a suitable material of a high heat conductivity, such as metal, being screwed thereon. a central recess 27 for receivingthe head`22. `When assembled, the cap 26 presses the fuse 23 toward the lower front-wall of the socket The described construction of the excess heat protector is designe-d for electromotors, transformers and other highly loaded apparat-us, as well as for generators. The shell 1 is screwed in a corresponding bore of the shell of the machine or pparatus to be protected from excess heat. conductor of the apparatus or the machine is connected The cap 26 is formed with `chines `or apparatus. l4 the current is obtained in the following to the terminal 3. The cap 26 surrounding the fuse 23 is to be arranged near that por`- tion of the machine or apparatus which is most exposed to the danger of excess heat, or it may be mounted immediately onv that portion, in order to quickly impart the temperature of superheating to the fuse, thereby 'causing the interruption of the electric current in due time, as will be described be-Y low. The cap 26 is fitted with a covering 28 of any heat insulating material, in order to prevent it from being cooled, especially on ventilated motors 'or other ventilated ma- The interruption of manner: At a certain temperature of excess heat the fuse 23 blows andallows the spring pressed plunger 12 to move upwardto the position shown, in Fig. 2, the bolts 6 leavingthe contact surfaces. The plunger 12 of insulating material enters between the contacts 5, thereby preventing the formation of an arc. lnorde'rl to repair the switch, the caps 20 ,and 26 vare removed and the socket 13 together ywith the plunger 12 are withdrawn from the' shell 1. After removing the remnants of the fuse, the head 17 is presseddo-wnward until the pin 21 projects from the. opening of the socket- 13. Thereon a new fuse is mounted von said pin, the socket 13 with the plug-is inserted again in the shell 1 and the caps 2O and 26 replaced.

The excess heat protector could also be multipolar. In this case `the plunger 12 would be fitted with a corresponding number of conducting bridges 6, 7. The excess heatprotector could also be formed in such manner that the current is closed by it instead of beinglinterrup'ted.' In this case, at the position` of the plunger 12 as shown in Fig. 1, the conducting bridge formed Vby the bolts 6 and the tube 7 would be displaced with regard to the contact surfaces 5. 'The bolts 6 would be mounted onthe spring pressedplunger 12V below the contacts 5 'andwould move between them Aonly when the fuses have blown, thereby causing for instance an electromagnetic switch in the circuit to operate. ,Y Y ,Y We claim: 1. A device of the lcharacter described, comprising a ltubular casing adapted for attachmentgto a `machine yto be protected Vto said sleeve ands` enclosingk said against excessive heat, a pair of electrical terminals ydisposed at diametrically oppositey points Vin said casing, an insulating' sleeve supported within the casing with one end thereof extending outside ofsaid casing, an .insulating plunger slidable within said sleeve, a cap threaded on said casing for retaining said sleeve therein, said cap being` perforated to permit the passage of the plunger therethrough, a pair of contact members carried by said plunger normally in Contacty with and closing a circuit through said terminals, a fusible member engaging said plunger and the extended Vend of the sleeve thereby to retain the plunger in cir-- cuit-closing position, resilient means in engagement with said plunger and adapted to move the same out of circuit-closing position upon removal of said fusible member, and a cap removably secured to said sleeve and enclosing said fusible member.

2. A device of the character described, comprising .aftubular casing adapted for attachment to a machineA to be protected against excessive heat, a pair of electrical terminals disposed at diametrically opposite points in said casing, an insulating sleeve supported within the casing with one end thereof extending outside of said casing, an insulating plunger slidable within said sleeve, a cap threaded on said casing for retaining said sleeve therein, said cap being perforated to permit the passage of the plunger therethrough, a pair of contac members carried by said plunger' normally in contact with and closing a circuit through said terminals, a pin secured in said plunger and having an enlarged head, a fusible` disk having a radial slot therein adapted to straddle said pin and engage said head, said disk being adapted also to engage the extended end of the sleeve therebyrto retain the plunger in circuit-closing position, resilient means in engagement with said plunger and adapt-ed to move the same out of cin cuit-closingposit-ion upon removal of said fusible disk, and a cap removably secured fusible disk.y f

In testimony that we claim the foregoing as our invention we havesigned our names.

` 'WILHELM HICKEL.

OTTO PLETSCHER, JUN. 

